Examination and treatment of complex cervical dystonia

Abstract

Introduction Botulinum neurotoxin (BoNT) serotype A (BoNT-A) is the treatment of choice for cervical dystonia (CD). Treatment outcome can vary with the presentation of CD and is significantly dependent on the correct assessment of the muscle involved. There are “simple” (movement disorders in one plane) and “complex” (movement disorder in two or more levels) forms of CD. The most common presentation is the rotation and tilting of the head. The difficulty lies in the treatment of complex CD. In large studies, rates of patient satisfaction with the BoNT therapy range from 50 to 60% (Comella et al ., 2000; Haussermann et al ., 2004; Truong et al ., 2010). The most common cause of unsatisfactory treatment is the selection of the wrong muscle. The selection of the treated muscles is most effective if the actual clinical picture of complex CD in a patient is considered as an individual situation. In a large study with imaging (MRI, CT) in patients with CD, it was noted that the previous phenomenological classification of CD in four groups (torticollis, laterocollis, antecollis and retrocollis) is inadequate. There are clinical cases of CD in which only muscles that act on the head are involved, and others involving only muscles that act on the cervical spine (Reichel, 2009, 2012). Therefore, a more extensive complex cervical movement disorder clinical analysis beyond the four traditional groups is required. The objective is a precise delineation of an optimal individualized treatment strategy in the selection of muscle involved. As the selection of the treated muscles and finding the individual BoNT dose can be difficult, different diagnostic methods are used. They include ultrasound, CT neck soft tissue imaging (particularly the deep muscles of the neck), electromyography (EMG) of neck muscles and standardized photographs of patients with measurements of angles (head, neck, thorax). The presence of a lateral shift or forward sagittal shift (very rarely backward) suggests a combination of two clinical pictures: lateral shift occurs when a laterocollis is combined with a laterocaput to the opposite side (Fig. 6.1a). A sagittal shift forward occurs when an antecollis is combined with a retrocaput. A sagittal shift to the rear is also possible (combination of retrocollis and antecaput) but occurs very rarely isolated, most likely with generalized dystonia.